Carrying bags such as backpacks and duffel bags are designed in various sizes and shapes. Some have multiple pockets and are designed to accommodate various articles of various sizes. The helmet design and manufacturing industry strives to provide protective and attractive helmets for cyclists. Since helmets can be awkward to carry when not being worn, some backpacks are designed to accommodate cyclists' helmets.
One concern in designing carrying bags is efficient use of space. Backpacks and duffel bags, for example, should be designed such that they are no larger than required yet can store many objects in that space. Expandable compartments are typically used to serve this purpose. When they are not in use, the expandable compartments are typically zipped shut and do not take up that much extra space.
Conventional expandable compartments suffer from some problems. First, typically the material around the perimeter of the pocket which allows the expansion is such that it does no permit an easy compression of the pocket when the pocket will be zipped close. This sometimes occurs because the material does not fold easily onto itself when the pocket is in the closed position. Second, typical expandable compartments consist of one outer panel attached to a perimeter panel. The one outer panel is typically flat and may not efficiently and aesthetically accommodate items of various sizes and shapes. Moreover, this outer panel typically is attached to the backpack on all of its (the outer panel's) sides, and this contributes to the lack of such various size accommodations.
Since backpacks can be worn be persons of different sizes, adjustability in the straps attaching the backpack to a user is also a desirable feature.
There exists a need to provide a carrying bag which allows transport of objects of varying sizes in an expandable compartment.